Fluid pressure regulating valves

ABSTRACT

This invention relates to a fluid pressure regulating valve particularly for regulating the pressure of liquid fuel fed to the injector in a fuel injection system of an internal combustion engine. In the valve fluid passes from an inlet passage to an outlet passage through an aperture and the size of the aperture is controlled by a member having an area on which the inlet fluid pressure acts in opposition to a bias means, whereby to regulate the pressure, and the member is arranged to be subject to negligible net force, in a direction which would alter the aperture size, due to variations in pressure of the outlet fluid.

United States Patent [1 1 Croft Nov. 20, 1973 FLUID PRESSURE REGULATINGVALVES [75] Inventor: Brian Hugh Croft, Coventry.

England 7 [73] Assignee: Brico Engineering Limited,

Coventry, England [22] Filed: Aug. 9, 1971 21 Appl. No.: 170,039

1,363,623 12/1920 Smith 137/538 X 1,377,199 5/1921 Granby 137/536 XPrimary ExaminerHenry T. Klinksiek Attorney-Holcombe, Wetherill &Brisebois [5 7] ABSTRACT This invention relates to a fluid pressureregulating valve particularly for regulating the pressure of liquid fuelfed to the injector in a fuel injection system of an internal combustionengine. In the valve fluid passes from an inlet passage to an outletpassage through an aperture and the size of the aperture is controlledby a member having an area on which the inlet fluid pressure acts inopposition to a bias means, whereby to regulate the pressure, and themember is arranged to be subject to negligible net force, in a directionwhich would alter the aperture size, due to variations in pressure ofthe outlet fluid.

2 Claims, 1 Drawing Figure FLUID PRESSURE REGULATING VALVES Thisinvention relates to a fluid pressure regulating valve and is applicableparticularly, but not exclusively, to a valve for regulating thepressure of liquid fuel fed to the injector in a fuel injection systemof an internal combustion engine.

According to one aspect of the invention, in a fluid pressure regulatingvalve fluid passes from an inlet passage to an outlet passage through anaperture, the size of the aperture being controlled by a member havingan area on which the inlet fluid pressure acts in opposition to a biasmeans, whereby to regulate the pressure, and in which the member isarranged to be subject to negligible net force, in a direction whichwould alter the aperture size, due to variations in pressure of theoutlet fluid.

Suitably the member is arranged to have a total effective area in anopposite direction exposed to the outlet fluid pressure which areabalances the total effective area of the member exposed to the outletfluid pressure in the first-mentioned direction.

Conveniently the member includes a plunger which is movable axiallytowards the aperture to reduce the latter, and downstream of theaperture the plunger has a reduced effective area compared with itseffective area at the aperture, whereby the outlet pressure acting onthe difference in area between the reduced effective area and theaperture area will generate a force urging the plunger towards theaperture, and a diaphragm arranged to allow the axial movement of theplunger is sealed to the plunger and the valve body at the opposite sideof the outlet from the aperture, the diaphragm being arranged whensubject to the outlet pressure to generate a force on the plunger equaland opposite to the force urging the plunger towards the aperture.Preferably the member is axially slidable in the body.

According to another aspect of the invention a fuel injection system,for an internal combustion engine, includes any of the above-mentionedfluid pressure regulating valves, for regulating the pressure of fuelfed to the injector.

The invention is described, by way of example only, with reference tothe accompanying drawing which is an axial section through oneembodiment of the invention.

In the drawing a valve, for regulating the pressure of liquid fuel fedto the injector in a fuel injection system of an internal combustionengine, has a body in which are formed fuel inlet and outlet passages11, 12, respectively. The passages 11, 12 are joined by a bore 13 whichterminates in a larger concentric bore 14 adjacent the outlet passage12. The junction of the bores 13, 14 is a shoulder having a sharp corner15.

A hollow cylindrical plunger 16 is an accurate sliding fit in the bore13 and is urged towards the blind end 17 of the bore 13 by a low ratepre-compressed helical spring 18.

The spring 18 reacts against a thimble 19 mounted on the end of anadjusting screw 20. The latter is screwed into an end cap 21 which isheld to the body 10 by a nut 22 to close the outlet end of the bores 13,14. The plunger 16 has a circumferential groove 23 formed with a sharpcorner 24 which aligns with the sharp corner when the plunger 16 is incontact with the blind end 17 of the body 10. The groove 23 communicateswith the inlet passage 11 by longitudinal grooves 25 formed in theplunger 16.

When pressurised fuel is admitted through the inlet passage 11 itproduces an axial force on the plunger 16 which moves it to the right inthe FIGURE to open an aperture between the sharp corners 15, 24. Due tothe low rate of the spring 18 the pressure of inlet fuel increases thisaperture until the fuel flowing therethrough has the desired regulatedinlet pressure.

Fuel having passed through the regulating aperture escapes through thelarger bore 14 and outlet passage 12.

The interior of the plunger 16 and the end space 28 of the bore 14adjacent the end cap 21 is vented to atmosphere, inlet manifold pressureor other suitable standard pressure, through a bore 26 in the adjustingscrew 20 which is locked by a lock nut 27. To prevent the escape of fuelthrough the end space 28 and bore 26, the plunger 16 is sealed to thebody 10 by a rubberlike or other suitable diaphragm 29. The diaphragm 29is held against an end face of the body 10 by the end cap 21 and is heldagainst the right hand end face of the plunger 16 by a shouldered sleeve30 screwed into the plunger 16.

Downstream of the regulating aperture the plunger 16 has a reduceddiameter portion 31. Any backpressure obtaining in the outlet passage 12will act on the difference in area between the plunger 16 at the sharpshoulder 24 and at the reduced diameter portion 31 to produce forcetending to urge the plunger 16 towards the left in the FIGURE.Simultaneously the outlet back-pressure acts on the diaphragm 29 to produce a force on the plunger 16 tending to move the latter to the right.By careful selection of the inner and outer diameters of that part ofthe diaphragm 29 exposed to the outlet back-pressure, it is possible toequate the opposing forces on the plunger 16 due to the outletback-pressure. By this means the pressure regulating valve will adjustthe pressure on its inlet passage 1 l to a value which is substantiallyindependent of any variations in the pressure of the fuel passingthrough the outlet passage 12.

Although the invention has been described as applied to a valve in whichpressure regulationis effected by an aperture formed between sharpcomers, it is applicable to any other pressure regulating valve having adifferent type of aperture and may be used to regulate the pressure ofgases, vapours or liquids.

I claim:

1. In a fluid pressure regulating valve comprising a valve body havingan inlet passage, an outlet passage, an aperture between said inletpassage and said outlet passage, a member for controlling the size ofthe aperture, and a bias means acting on said member to close saidaperture, said member having an area on which the inlet fluid pressureacts in opposition to said bias means, the improvement according towhich said member comprises a plunger which is axially slidable in abore in the valve body, said bore communicating with the inlet passageand terminating in a larger concentric bore communicating with theoutlet passage, said aperture being defined between a circumferentialgroove in the surface of the plunger and the corner formed by the changein diameter of the bores in the valve body, the surface of the plungerbeing provided with axially extending grooves which communicate withsaid circumferential groove and extend towards said inlet passage,

and said plunger being provided with a cavity containing a helicalspring forming said bias means and which reacts against an adjustingmember extending through said valve body, said adjusting member servingto ad just the force exerted by the spring, and in which said plungerhas a reduced effective area downstream of said aperture as comparedwith its effective area at the aperture whereby outlet back pressureacting on the difference in area between said reduced effective area andthe effective area at said aperture will generate a force urging theplunger towards the aperture, and a diaphragm is connected to saidplunger at the opposite side of said outlet passage from said aperture,said diaphragm being arranged, when subjected to said back pressure, togenerate a force on the plunger equal and opposite to the force exertedon said difference in area.

2. A valve as claimed in claim 1, wherein the adjusting member containsa passage communicating with the cavity in the plunger whereby thecavity can be vented to atmosphere or another suitable standard pressureand a cap clamping the periphery of the diaphragm against the valvebody, said cap having a threaded bore into which screws a threaded rodforming the adjusting member and which is provided with the passagetherethrough.

1. In a fluid pressure regulating valve comprising a valve body havingan inlet passage, an outlet passage, an aperture between said inletpassage and said outlet passage, a member for controlling the size ofthe aperture, and a bias means acting on said member to close saidaperture, said member having an area on which the inlet fluid pressureacts in opposition to said bias means, the improvement according towhich said member comprises a plunger which is axially slidable in abore in the valve body, said bore communicating with the inlet passageand terminating in a larger concentric bore communicating with theoutlet passage, said aperture being defined between a circumferentialgroove in the surface of the plunger and the corner formed by the changein diameter of the bores in the valve body, the surface of the plungerbeing provided with axially extending grooves which communicate withsaid circumferential groove and extend towards said inlet passage, andsaid plunger being provided with a cavity containing a helical springforming said bias means and which reacts against an adjusting memberextending through said Valve body, said adjusting member serving toadjust the force exerted by the spring, and in which said plunger has areduced effective area downstream of said aperture as compared with itseffective area at the aperture whereby outlet back pressure acting onthe difference in area between said reduced effective area and theeffective area at said aperture will generate a force urging the plungertowards the aperture, and a diaphragm is connected to said plunger atthe opposite side of said outlet passage from said aperture, saiddiaphragm being arranged, when subjected to said back pressure, togenerate a force on the plunger equal and opposite to the force exertedon said difference in area.
 2. A valve as claimed in claim 1, whereinthe adjusting member contains a passage communicating with the cavity inthe plunger whereby the cavity can be vented to atmosphere or anothersuitable standard pressure and a cap clamping the periphery of thediaphragm against the valve body, said cap having a threaded bore intowhich screws a threaded rod forming the adjusting member and which isprovided with the passage therethrough.